Refrigerator Having Multi-Cycle Refrigeration System And Control Method Thereof

ABSTRACT

The present invention discloses a refrigerator having multi-cycle refrigeration system, comprises a main control circuit, a temperature sensor and a refrigeration cycle loop, wherein the main refrigeration cycle loop is composed of a compressor, a condenser, a main capillary, a freezing evaporator, a refrigerating evaporator and a gas returning pipe connected in series, and wherein, an auxiliary refrigerating cycle branch, which can be controlled independently, is added to refrigerating chamber, i.e. the magnet valve is connected to the downstream of the condenser, and the magnet valve has two output ports, one of which is connected to the main capillary, and the other is connected to an auxiliary refrigerating cycle branch, and the downstream of the branch is connected to the gas returning pipe. The present invention solves the contradiction between the refrigeration efficiency and the function of stopping freezing, and it can optimize the system efficiency in the normal using state in which the refrigerating chamber and the freezing chamber are used simultaneously and reduce the power consumption effectively, and at the same time it can further realize the function of closing the freezing chamber and convert the refrigerating chamber into a freezing chamber of different gradation.

FIELD OF THE INVENTION

The present invention relates to a refrigerator, in particular, it relates to a refrigerator having a compression device provided with several refrigeration loops arranged in series or in parallel.

BACKGROUND OF THE INVENTION

Prior Art I: The refrigerating and freezing chamber of common compression refrigeration system, of which the cycle refrigeration loop is a single system. With reference to FIG. 1, the outlet of compressor 1 is connected to condenser 2, the downstream of condenser 2 is connected to throttle capillary 3, the downstream of capillary 3 is connected to freezing evaporator 4 then to refrigerating evaporator 5, or refrigerating evaporator 5 then to freezing evaporator 4, and is finally connected to compressor 1 through gas returning pipe 6.

The operation principle of Prior Art I is as follows: The operation of compressor 1 is controlled by a temperature sensor provided in the refrigerating chamber. When the temperature of the refrigerating chamber is higher than the predefined startup temperature, the compressor begins to operate, and the temperatures of the two chambers drop simultaneously; when the temperature of the refrigerating chamber is lower than the predefined halt temperature, the compressor ceases to operate and the temperatures of the two chambers rise simultaneously. When the temperature of the refrigerating chamber rises back to a point which is higher than the predefined startup temperature, the compressor begins to operate again, and this process repeats to keep the temperatures of the refrigerating chamber within a certain temperature range.

The system possesses a simple structure, and its operation is controlled by the temperature of the refrigerating chamber, and the temperature of the freezing chamber cannot be controlled independently and it varies with the change in the temperature of the surrounding environment. Generally, the surrounding temperature rises during summertime, and the temperature of the freezing chamber is too low, it will consume more cooling capacity; and during wintertime the surrounding temperature is so low that the operation frequency required by refrigerating chamber is low while the temperature of the freezing chamber is too high, and the common solution is to add auxiliary heating device, which compels a cycle start up to reduce the temperature of freezing chamber. Obviously, the auxiliary heating device consumes extra energy.

Prior Art II: Traditional dual system topology, generally bases on the above-mentioned topology structure that connects the refrigerating before the freezing, having the input port of the magnet valve 31 connected to the end of condenser 2. With the reference to FIG. 2, the magnet valve 31 is provided with two output ports, one of which is connected to the refrigerating throttle capillary 3, and the other is connected to the auxiliary freezing throttle capillary 34, the end of capillary 34 is connected to the output port of refrigerating evaporator 5 and the input port of freezing evaporator 4, and the end of freezing evaporator 4 is connected to the gas returning end of compressor 1 through the gas returning pipe 6.

The operation principle of Prior Art II is as follows: The operation of compressor 1 is controlled by the temperature sensor provided in the refrigerating chamber. When the temperature of the refrigerating chamber is higher than the predefined startup temperature, the compressor begins to operate and the temperatures of the two chambers drop simultaneously; when the temperature of the refrigerating chamber is lower than the predefined halt temperature, the compressor ceases to operate and the temperatures of the two chambers rise simultaneously. When the temperature of the freezing chamber rises due to fast cooling or low surrounding temperature, the auxiliary freezing cycle will be started to reduce the temperature of freezing chamber independently. Compared with the cycle loop of common single system, the dual system excludes the auxiliary heating device, and when the surrounding temperature is low, energy will be saved.

The advantages of the refrigerating and freezing chamber of dual system lie in that the refrigerating chamber can be closed down, and the freezing chamber can be utilized independently. Meanwhile, the system possesses large cooling capacity, because freezing chamber has independent capillary throttle control device. This art has been widely applied.

Prior Art III: In order to close down the freezing chamber and utilize the refrigerating chamber independently, a parallel topology structure has been proposed by some prior inventions. With reference to FIG. 3, the topology structure is characterized in that the refrigerating and freezing adopt two independent throttle and evaporating refrigeration loops. The topology structure is simple, and can operate the refrigerating and freezing refrigeration loop independently thereby save energy. However, in its normal use, i.e. when refrigerating and freezing are operating simultaneously, since the workload varies greatly, evaporation pressure and temperature deviates largely from the optimum value, which causes the system efficiency to decrease, and causes energy consumption to rise.

SUMMARY OF THE INVENTION

The new topology structure refrigeration system of the said “composite multi-cycle” according to the present invention successfully solves the contradiction existing between refrigeration efficiency and the function of stopping freezing, and it can optimize the system efficiency in the normal operational state, in which the refrigerating chamber and the freezing chamber are used simultaneously and reduce the power consumption effectively. Meanwhile, it can further realize the function of closing the freezing chamber and converting the refrigerating chamber into a freezing chamber of the different classes. The said “composite”, means that “multiple” refrigeration system loop and chambers are “independently” controlled.

The refrigerator having multi-cycle refrigeration system according to the present invention is implemented as follows: it comprises a main CPU, a temperature sensor and a refrigeration cycle loop, wherein the refrigeration cycle loop is composed of a compressor, a condenser, a main capillary, a freezing evaporator, a refrigerating evaporator and a gas returning pipe which are connected in series, and a magnet valve having two output ports is connected to the downstream of the condenser, and one of the output ports is connected to the main capillary and the other is connected to an auxiliary refrigerating cycle branch. The solution can be realized in details by following structures:

Firstly, in the refrigeration cycle loop, the freezing evaporator is connected before the refrigerating evaporator; the auxiliary refrigerating cycle branch comprises auxiliary refrigerating capillary, which is in parallel with the main capillary and the freezing evaporator that are connected in series, and which is connected between the output port of the magnet valve and the input port of the refrigerating evaporator.

Secondly, in the refrigeration cycle loop, the freezing evaporator is connected before the refrigerating evaporator; auxiliary refrigerating cycle branch comprises auxiliary capillary and auxiliary refrigerating evaporator connected thereof in series, and the auxiliary refrigerating cycle branch is in parallel with the main capillary and the freezing evaporator that are connected in series, and which is connected between the output port of the magnet valve and the input port of the refrigerating evaporator.

Thirdly, in the refrigeration cycle loop, the freezing evaporator is connected before the refrigerating evaporator; auxiliary refrigerating cycle branch comprises auxiliary capillary and auxiliary refrigerating evaporator connected thereof in series, and the auxiliary refrigerating cycle branch is in parallel with the main capillary, the freezing evaporator and the refrigerating evaporator that are connected in series, and which is connected between the output port of the magnet valve and the output port of the refrigerating evaporator.

Fourthly, in the refrigeration cycle loop, the refrigerating evaporator is connected before the freezing evaporator; auxiliary refrigerating cycle branch comprises auxiliary capillary and auxiliary refrigerating evaporator connected thereof in series, and the auxiliary refrigerating cycle branch is in parallel with main capillary, refrigerating evaporator and freezing evaporator that are connected in series, and which is connected between the output port of the magnet valve and the output port of the freezing evaporator.

Wherein, the magnet valve is a two-position three-way valve, which is connected to condenser, main capillary and auxiliary refrigerating capillary respectively. In order to implement the above structure, magnet valve is two magnet valves in parallel installation, one of which is connected between the condenser and the main capillary, and the other is connected between the condenser and the auxiliary refrigerating capillary.

The control method according to the present invention comprises steps:

I. The refrigerator is electrified and initialized, main CPU tests whether “Freezing Off” is activated, if it is activated, then the magnet valve switches off the freezing cycle loop and switches on the auxiliary refrigerating cycle loop simultaneously, when the predefined temperature of refrigerating chamber is reached, it returns to the beginning to repeat the test; if “Freezing Off” is not activated, the magnet valve switches on freezing cycle loop and switches off auxiliary refrigerating cycle loop, and it proceeds to Step II;

II. The temperatures of refrigerating chamber and freezing chamber are tested, and when the temperature of the refrigerating chamber or the temperature of the freezing chamber is higher than the predefined startup temperature, compressor is initiated; if the temperature of the freezing chamber is too low and the temperature of the refrigerating chamber is higher than the predefined startup temperature, the magnet valve switches off the freezing cycle loop and switches on the auxiliary refrigerating cycle loop to reduce the temperature of the refrigerating chamber to the predefined temperature, then it returns to Step I.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 is the structural block diagram according to the prior art I;

FIG. 2 is the structural block diagram according to the prior art II;

FIG. 3 is the structural block diagram according to the prior art III;

FIG. 4 is the structural block diagram of the embodiment 1 according to the present invention;

FIG. 5 is the structural block diagram of the embodiment 2 according to the present invention;

FIG. 6 is the structural block diagram of the embodiment 3 according to the present invention;

FIG. 7 is the structural block diagram of the embodiment 4 according to the present invention;

FIG. 8 is the structural block diagram of the embodiment 5 according to the present invention;

DETAILED DESCRIPTION OF THE INVENTION Embodiment 1

The present embodiment provides a typical system of topology structure according to the present invention, which comprises a main CPU, a temperature sensor and a refrigeration cycle loop. With the reference to FIG. 4, the refrigeration cycle loop is composed of a compressor 1, a condenser 2, a main capillary 3, a freezing evaporator 41, a refrigerating evaporator 51 and a gas returning pipe 6 which are in turn connected in series accordingly, and the downstream of the condenser 2 is connected in series to a magnet valve 31 having two output ports, one of which is connected to the main capillary 3, and the other is connected to the auxiliary refrigerating cycle branch, the auxiliary refrigerating cycle branch comprises auxiliary refrigerating capillary 32, which is in parallel with the main capillary 3 and the freezing evaporator 41 that are themselves connected in series, and the auxiliary refrigerating capillary 32 is connected between the output port of the magnet valve 31 and the input port of the refrigerating evaporator 51.

Compared with the traditional dual system as shown in FIG. 2, the difference of the Embodiment 1 lies in that, in the loop, the freezing evaporator 41 is connected before refrigerating evaporator 51.

The refrigerant cycle system of the present invention flows in the following manner:

After the refrigerator is initiated, the compressor begins to operate, the refrigerant is compressed into high-pressure gas by compressor 1 and is discharged, and the high-pressure gas passes through magnet valve 31 after being condensed by the condenser 2. The temperature sensor detects the temperatures of the freezing chamber and that of the refrigerating chamber, when the freezing chamber and the refrigerating chamber require to operate simultaneously, the CPU controls the magnet valve 31 to switch on freezing and switch off refrigerating, the refrigerant is compressed into high-pressure gas by compressor 1 and is discharged, and the high-pressure gas passes through magnet valve 31 after being condensed by condenser 2. The refrigerant is throttled by the main capillary 3, and becomes low-pressure low-temperature liquid. The liquid partially evaporates into low-temperature gas in the freezing evaporator 41 to absorb the heat energy of freezing chamber F. The remaining liquid, which does not evaporate completely, flows into the refrigerating evaporator 51 and continues to evaporate, and to absorb the heat energy of the refrigerating chamber R, and finally evaporates into low-temperature gas completely, which is then inhaled into compressor 1 after being heated by the gas returning pipe 6, and thereby forms the cycle; here refrigerating and freezing are involved in the cycle simultaneously, which can be utilized as refrigerator of common practice. In respect that the system load is the load of refrigerating and freezing in series, which is constant, therefore, the refrigeration system cycle efficiency can be adjusted to an optimum status under the target surrounding temperature, and effectively enhance energy conversion rate.

When there are large amount of food stored in the refrigerating chamber which thereby needs more cooling capacity, the CPU controls the magnet valve 31 to switch on freezing and auxiliary refrigerating cycle, the refrigerant is compressed into high-pressure gas by compressor 1 and is discharged, and the high-pressure gas passes through the magnet valve 31 after being condensed by condenser 2. The refrigerant is throttled by the main capillary 3, and becomes low-pressure low-temperature liquid. The liquid partially evaporates into low-temperature gas in the freezing evaporator 41 to absorb the heat energy of the freezing chamber F. The remaining liquid, which does not evaporate completely, flows into the refrigerating evaporator 51 and continues to evaporate to absorb the heat energy of refrigerating chamber R. Meanwhile, the refrigerant is throttled by throttle capillary 32 of the auxiliary refrigerating cycle, and becomes low-pressure low-temperature liquid. The liquid evaporates into low-temperature gas in the refrigerating evaporator 51 to absorb the heat energy of refrigerating chamber R. The liquid finally evaporates into low-temperature gas completely, which is inhaled into compressor 1 after being heated by gas returning pipe 6, and thereby forms the cycle; here the temperature of refrigerating chamber can be decreased, which realizes the function of fast cooling for one aspect, and realizes the function of converting the refrigerating chamber into freezing chamber for another aspect. It is particularly suitable for storing large amount of frozen food periodically. The freezing temperature of the refrigerating chamber can be regulated by adjusting the duration of switch on and off of the magnet valve 31, and this is a very practical function, which is also very suitable for the use of Chinese people.

When the temperature of the freezing chamber has reached the predefined temperature while the refrigerating chamber has not yet reached that temperature, the CPU controls the magnet valve 31 to switch off the freezing and switch on the auxiliary refrigerating cycle, the refrigerant is throttled by the throttle capillary 32 of auxiliary refrigerating cycle, and becomes low-pressure low-temperature liquid. The liquid evaporates into low-temperature gas in the refrigerating evaporator 51 to absorb the heat energy of the refrigerating chamber R. The liquid finally evaporates into low-temperature gas completely, which is inhaled into compressor 1 after being heated by gas returning pipe 6, and thereby forms cycle; here the freezing evaporator is not involved in refrigeration cycle, and refrigerating generates all the cooling capacity, which can be utilized as refrigerating chamber, to largely reduce the electricity consumption and save energy. This is a very practical function.

The magnet valve 31 according to the present invention is provided as a two-position three-way valve.

In the refrigerator according to the present invention, the refrigerating evaporator 51 and the freezing evaporator 41 comprise single evaporator and a combination of several evaporators in series for chambers with same or different temperatures.

The typical matching strategy of the refrigerator according to the present invention is as follows:

The main operation control of the compressor adopts refrigerating temperature sensor, and system matching principle is, under the target surrounding temperature (for example, 25□, or other temperatures, according to the average surrounding temperature of the target market or the climate type the refrigerator is designed for), to reach the refrigerating target temperature (for example, 5□) and the freezing target temperature (for example, −18□) simultaneously, and to further enhance the cycle system efficiency of the refrigerant and enable the refrigerator to reach the optimal energy saving target under the common target surrounding temperature when the refrigerating and the freezing are operating simultaneously.

The typical temperature control strategy of the refrigerator according to the present invention is as follows: As surrounding temperature rises or refrigerating load changes, the refrigerating temperature rises to a point which is higher than a certain level (the refrigerating target temperature+X), then the magnet valve of the auxiliary refrigerating cycle loop will be switched on to reduce the temperature of the refrigerating chamber solely and reach the refrigerating target temperature. When freezing temperature drops to a point which is lower than a certain level (the freezing target temperature−Y), the magnet valve of the freezing will be switched off to cut off the freezing cycle loop and reduce the energy loss. Generally, X is between 1˜3□, and Y is between 2˜5□.

The typical temperature control program of the refrigerator according to the present invention is as follows:

Program resets to START, tests whether “Freezing Off” is activated, if it is activated, then the magnet valve switches off the freezing cycle loop and switches on the auxiliary refrigerating cycle loop. It is a “Refrigerating” single cycle loop, which operates according to the predefined temperature of the “Refrigerating Chamber”, and the scope of the predefined temperature can be large.

If “Freezing Off” is not activated, the magnet valve switches on the freezing cycle loop and switches off the auxiliary refrigerating cycle loop. The temperatures of refrigerating chamber and freezing chamber are tested, and when the temperature of the refrigerating chamber or the temperature of the freezing chamber is higher than the predefined startup temperature, compressor is initiated. If the temperature of the freezing chamber is too low (freezing target temperature−Y) while the temperature of the refrigerating chamber is higher than the predefined startup temperature, the magnet valve switches off the freezing cycle loop and switches on the auxiliary refrigerating cycle loop to reduce the temperature of the refrigerating chamber.

Embodiment 2

With reference to FIG. 5, the difference between the present embodiment and the embodiment 1 lies in that, the magnet valve 31 of the present embodiment is two magnet valves in parallel installation, one of which is connected between the condenser 2 and the main capillary 3, and the other is connected between the condenser 2 and the auxiliary refrigerating capillary 32, these two valves control respectively the freezing cycle loop and the auxiliary refrigerating cycle branch, and the other parts of embodiment 2 are the same as that of the embodiment 1.

Embodiment 3

With reference to FIG. 6, the difference between the present embodiment and the above-mentioned embodiments lies in that, the auxiliary refrigerating evaporator 52 is connected to the downstream of the auxiliary refrigerating capillary 32 in series, in such a way, the auxiliary refrigerating cycle branch comprises the auxiliary capillary 32 and the auxiliary refrigerating evaporator 52 connected thereof, the auxiliary refrigerating cycle branch is in parallel with the main capillary 3 and freezing evaporator 41 that are themselves connected in series, and is connected between the output port of the magnet valve 31 and the output port of the freezing evaporator 41. Compared with the above-mentioned two embodiments, the present embodiment further reduces the temperature of the refrigerating chamber to convert the refrigerating chamber to icebox, one-star or two-star freezing chamber, and the predefined temperature scope can be large.

Embodiments 4

The present embodiment provides a typical system topology structure according to the present invention, which is completely different from the traditional dual system.

With reference to FIG. 7, the difference between the present embodiment and embodiment 3 lies in that, the auxiliary refrigerating cycle branch is in parallel with the main capillary 3, freezing evaporator 41 and refrigerating evaporator 51 orderly that are themselves connected in series, and is connected between the output port of the magnet valve 31 and the output port of the refrigerating evaporator 51, i.e. the end of the auxiliary refrigerating cycle branch is connected to the input port of the gas returning pipe.

The refrigerant cycle system of the present invention flows in the following manner:

The control process of the refrigerator according to the present invention is that, after the refrigerator is electrified and initialized, the temperature sensor begins to test the temperatures of the chambers, and when refrigerating chamber and freezing chamber require to begin operating simultaneously, the main CPU controls the magnet valve 31 to switch on the main cycle and switch off the auxiliary refrigerating cycle, and refrigerant cycle is the same as common refrigerator system in that the freezing chamber and the refrigerating chamber refrigerate simultaneously. The refrigerant is compressed into high-pressure gas by compressor 1 and is discharged, and the high-pressure gas passes through magnet valve 31 after being condensed by condenser 2. The refrigerant is throttled by the main capillary 3, and becomes low-pressure low-temperature liquid. The liquid partially evaporates into low-temperature gas in the freezing evaporator 41 to absorb the heat energy of the freezing chamber F. The remaining liquid, which does not evaporate, flows into the refrigerating evaporator 51 and continues to evaporate, to absorb the heat energy of the refrigerating chamber R, and finally evaporates into low-temperature gas completely, which is inhaled into the compressor 1 after being heated by gas returning pipe 6, and thereby forms the cycle; here refrigerating and freezing are involved in the cycle simultaneously, which can be utilized as refrigerator of common practice. In respect that the system load is the load of refrigerating and freezing in series, which is constant, therefore, the refrigeration system cycle efficiency can be adjusted into an optimum efficiency under the target surrounding temperature, and effectively enhance the energy conversion rate.

When refrigerating chamber needs more cooling capacity, the main CPU controls the magnet valve 31 to switch on the main cycle and the auxiliary refrigerating cycle; the refrigerant is compressed into high-pressure gas by the compressor 1 and is discharged, and the high-pressure gas passes through the magnet valve 31 after being condensed by the condenser 2. The refrigerant is throttled by the main capillary 3, and becomes low-pressure low-temperature liquid. The liquid partially evaporates into low-temperature gas in the freezing evaporator 41 to absorb the heat energy of freezing chamber F. The remaining liquid, which does not evaporate, flows into the refrigerating evaporator 51 and continues to evaporate to absorb the heat energy of the refrigerating chamber R. Meanwhile, the refrigerant is throttled by the auxiliary refrigerating capillary 32, and becomes low-pressure low-temperature liquid. The liquid evaporates into low-temperature gas in auxiliary refrigerating evaporator 52 to absorb the heat energy of the refrigerating chamber R. The liquid finally evaporates into low-temperature gas completely, which is inhaled into compressor 1 after being heated by gas returning pipe 6, and thereby forms cycle; here the temperature of refrigerating chamber can be decreased, which realizes the function of fast cooling for one aspect, and realizes the function of converting the refrigerating chamber into freezing chamber for another aspect. It is particularly suitable for storing large amount of frozen food periodically. The freezing temperature of the refrigerating chamber can be regulated by adjusting the duration of switch on and off of the magnet valve 31, and this is a very practical function, which is also very suitable for the use of Chinese people.

When the freezing chamber has reached the predefined temperature or shuts down, while the refrigerating chamber needs cooling capacity, the CPU can control the magnet valve to switch off freezing cycle and switch on auxiliary refrigerating cycle branch, the refrigerant is throttled by the auxiliary refrigerating capillary 32 and becomes low-pressure low-temperature liquid. The liquid evaporates into low-temperature gas in the auxiliary refrigerating evaporator 52 to absorb the heat energy of the refrigerating chamber R. The liquid finally evaporates into low-temperature gas completely, which is inhaled into compressor 1 after being heated by gas returning pipe 6, and thereby forms cycle; here the freezing evaporator 41 and refrigerating evaporator 51 are not involved in refrigeration cycle, and auxiliary refrigerating evaporator 52 generates all the cooling capacity, which can be utilized as refrigerating chamber, to largely reduce the electricity consumption and save energy. This is a very practical function.

The matching strategy of the refrigerator according to the present invention is as follows:

The main operation control of the compressor adopts refrigerating temperature sensor, and system matching principle is, under the target surrounding temperature (for example, 25□, or other temperatures, according to the average surrounding temperature of the target market or the climate type the refrigerator is designed for), to reach the refrigerating target temperature (for example, 5□) and freezing target temperature (for example, −18□) simultaneously, and to further enhance the cycle system efficiency of the refrigerant and enable the refrigerator to reach the optimal energy saving target under the common target surrounding temperature when refrigerating and freezing are operating simultaneously.

The typical temperature control strategy of the refrigerator according to the present invention is as follows: When surrounding temperature rises or refrigerating load changes, the refrigerating temperature rises to a point which is higher than a certain level (refrigerating target temperature+X), then the magnet valve of the auxiliary refrigerating cycle loop will be switched on to reduce the temperature of the refrigerating chamber solely and reach the refrigerating target temperature. When freezing temperature drops to a point which is lower than a certain level (freezing target temperature−Y), the magnet valve of the freezing will be switched off to cut off the freezing cycle loop and reduce the energy loss. Generally, X is 1˜3□, and Y is 2˜5□.

Embodiments 5

With reference to FIG. 8, the difference between present embodiment and embodiment 4 lies in that, the auxiliary refrigerating cycle branch is still connected to the input port of the gas returning pipe, and the position of refrigerating evaporator 51 and that of freezing evaporator in the refrigeration loop shift with each other, so that the end of the auxiliary refrigerating cycle loop is connected between freezing evaporator 41 and gas returning pipe 6, and the other parts being the same as that of the embodiment 4.

The refrigerator according to the present invention, includes but is not limited to drawer type and shelf type of home refrigerating freezing refrigerator, regardless of the vertical and horizontal relative positions of the refrigerating chamber and the freezing chamber.

INDUSTRIAL PRACTICALBILITY

The refrigerator having multi-cycle refrigeration system and control method thereof can be applied in the manufacture of and use of various refrigerators with refrigerating and freezing chambers, and the industrial application has wide prospect. 

1. A refrigerator having multi-cycle refrigeration system, comprises a main control circuit, a temperature sensor and a refrigeration cycle loop, wherein the main refrigeration cycle loop is composed of a compressor, a condenser, a main capillary, a freezing evaporator, a refrigerating evaporator and a gas returning pipe connected in series, and wherein, an auxiliary refrigerating cycle branch, which can be controlled independently, is added to refrigerating chamber, i.e. the magnet valve is connected to the downstream of the condenser, and the magnet valve has two output ports, one of which is connected to the main capillary, and the other is connected to an auxiliary refrigerating cycle branch, and the downstream of the branch is connected to the gas returning pipe.
 2. The refrigerator having multi-cycle refrigeration system according to claim 1, wherein, in the refrigeration cycle loop, the freezing evaporator is connected before the refrigerating evaporator; the auxiliary refrigerating cycle branch comprises auxiliary capillary and auxiliary refrigerating evaporator connected thereof in series, and the auxiliary refrigerating cycle branch is in parallel with main capillary, freezing evaporator and refrigerating evaporator that are themselves connected in series, and is connected between the output port of the magnet valve and the output port of the refrigerating evaporator, i.e. the inlet of the gas returning pipe.
 3. The refrigerator having multi-cycle refrigeration system according to claim 1, wherein, in the refrigeration cycle loop, the refrigerating evaporator is connected before the freezing evaporator; auxiliary refrigerating cycle branch comprises auxiliary capillary and auxiliary refrigerating evaporator connected thereof in series, and the auxiliary refrigerating cycle branch is in parallel with main capillary, refrigerating evaporator and freezing evaporator that are themselves connected in series, and is connected between the output port of the magnet valve and the output port of the freezing evaporator, i.e. the inlet of the gas returning pipe.
 4. The refrigerator having multi-cycle refrigeration system according to claim 2, wherein, the magnet valve is a two-position three-way valve, which is connected respectively to the condenser, the main capillary and the auxiliary refrigerating capillary.
 5. The refrigerator having multi-cycle refrigeration system according to claim 3, wherein, the magnet valve is a two-position three-way valve, which is connected respectively to the condenser, the main capillary and the auxiliary refrigerating capillary.
 6. The refrigerator having multi-cycle refrigeration system according to claim 2, wherein, the magnet valve is comprising two magnet valves in parallel installation, one of which is connected between the condenser and the main capillary, and the other is connected between the condenser and the auxiliary refrigerating capillary.
 7. The refrigerator having multi-cycle refrigeration system according to claim 3, wherein, the magnet valve is comprising two magnet valves in parallel installation, one of which is connected between the condenser and the main capillary, and the other is connected between the condenser and the auxiliary refrigerating capillary.
 8. A method of controlling a refrigerator having multi-cycle refrigeration system according to claim 1, wherein, it comprises the following steps: I. The refrigerator is electrified and initialized, the main control circuit tests whether “Freezing Off” is activated, if it is activated, then the magnet valve switches off the main refrigeration cycle loop and switches on the auxiliary refrigerating cycle branch simultaneously, when the predefined temperature of refrigerating chamber is reached, it returns to the beginning to repeat the test; if “Freezing Off” is not activated, the magnet valve switches on freezing cycle loop and switches off auxiliary refrigerating cycle loop, and it proceeds to Step II; II. The temperatures of refrigerating chamber and freezing chamber are tested, and when the temperature of the refrigerating chamber or the temperature of the freezing chamber is higher than the predefined startup temperature, compressor is initiated; if the temperature of the freezing chamber is too low and the temperature of the refrigerating chamber is higher than the predefined startup temperature, the magnet valve switches off the freezing cycle loop and switches on the auxiliary refrigerating cycle loop, to reduce the temperature of the refrigerating chamber to the predefined temperature, then it returns to Step I. 